Split more code out of home.asm.

home/predef.asm

@@ -0,0 +1,50 @@
+Predef::
+; Call predefined function a.
+; To preserve other registers, have the
+; destination call GetPredefRegisters.
+
+	; Save the predef id for GetPredefPointer.
+	ld [wPredefID], a
+
+	; A hack for LoadDestinationWarpPosition.
+	; See Func_c754 (predef $19).
+	ld a, [H_LOADEDROMBANK]
+	ld [wPredefParentBank], a
+
+	push af
+	ld a, BANK(GetPredefPointer)
+	ld [H_LOADEDROMBANK], a
+	ld [$2000], a
+
+	call GetPredefPointer
+
+	ld a, [wPredefBank]
+	ld [H_LOADEDROMBANK], a
+	ld [$2000], a
+
+	ld de, .done
+	push de
+	jp [hl]
+.done
+
+	pop af
+	ld [H_LOADEDROMBANK], a
+	ld [$2000], a
+	ret
+
+GetPredefRegisters::
+; Restore the contents of register pairs
+; when GetPredefPointer was called.
+	ld a, [wPredefRegisters + 0]
+	ld h, a
+	ld a, [wPredefRegisters + 1]
+	ld l, a
+	ld a, [wPredefRegisters + 2]
+	ld d, a
+	ld a, [wPredefRegisters + 3]
+	ld e, a
+	ld a, [wPredefRegisters + 4]
+	ld b, a
+	ld a, [wPredefRegisters + 5]
+	ld c, a
+	ret